Rdiscrowd 5851 taskbrowse bookmarks dates

[n00rsy]

Issue number of the reported bug or feature request: RDISCROWD-5851

Describe your changes
Adds created and updated fields for each bookmark. New data structure in DB:

user.info = { 
             metadata...,
             taskbrowse_bookmarks : {
	                            project_name : {
			                         bookmark_name : {
                                                                   url: http://localhost:5000/project/proj/...
                                                                   created: 2023-04-05T17:59:28.516927
                                                                   updated: 2023-04-05T17:59:28.516927
			                         }
                                                 ....
		                    },
	                            project_name : {
			                         bookmark_name : {...,
                                                 bookmark_name : {...,
                                                 bookmark_name : {...
                                                 ....
		                    }
                                    ...
                  }
}

Example endpoint JSON response structure:

[
   {
      "created": "2023-04-26T18:17:29.745312",
      "name": "apple",
      "updated": "2023-04-26T18:17:29.745320",
      "url": "http://localhost:5000/project/testproject2/tasks/browse"
   },
{
      "created": "2023-04-06T18:17:29.745312",
      "name": "banana",
      "updated": "2023-04-06T18:17:29.745320",
      "url": "http://localhost:5000/project/testproject2/tasks/browse"
   },
]

Testing performed
Tested locally

Additional context

• RDISCROWD 5743 task browse bookmarks #832

[coveralls]

Pull Request Test Coverage Report for Build 4812350298

• 26 of 26 (100.0%) changed or added relevant lines in 1 file are covered.
• 30 unchanged lines in 5 files lost coverage.
• Overall coverage increased (+0.01%) to 94.122%

---

Files with Coverage Reduction	New Missed Lines	%
pybossa/api/init.py	1	97.53%
pybossa/task_creator_helper.py	1	98.15%
pybossa/api/task.py	5	93.62%
pybossa/importers/importer.py	6	97.01%
pybossa/repositories/task_repository.py	17	92.08%

Totals
Change from base Build 4564950531:	0.01%
Covered Lines:	16909
Relevant Lines:	17965

---

💛 - Coveralls

[dchhabda]

lgtm, thanks!